TRENTON — Tom MacArthur, the millionaire former mayor of Randolph, defeated conservative firebrand Steve Lonegan on Tuesday in a fiercely contested Republican primary fight between two North Jersey transplants seeking to replace a South Jersey congressman.

In the state’s other tight congressional primary, Assemblywoman Bonnie Watson Coleman (D-Mercer) won the Democratic nomination for a Central Jersey seat — and the chance to become New Jersey’s first female member of the House of Representatives in more than a decade.

Across New Jersey, the nine incumbents running for re-election easily won their primaries and are expected to regain their seats in November.

The 3rd District race for the seat being vacated by Republican U.S. Rep. Jon Runyan was one of the state’s nastiest races this year. At one point, Lonegan, the former mayor of Bogota, called MacArthur a “monster” over allegations that his insurance company played a part in shortchanging California wildfire victims. MacArthur characterized Lonegan, who lost to Cory Booker in the state’s special U.S. Senate election last year, as bitter.

MacArthur, a 53-year-old former insurance executive, put more than $2 million of his own money into the race, accounting for more than 99 percent of his donations. He was endorsed by Runyan and most of the elected officials and party leaders around the district, which covers parts of Burlington and Ocean County.

In the end, MacArthur drew about 60 percent of the vote Tuesday, while Lonegan had 40.

“I pledge today to be a different kind of congressman,” MacArthur said. “One who will care more about solutions than finger-pointing and bring people together to restore our country and get America working again.”

The race marked the sixth time Lonegan has lost a primary or general election, and, with his defeat by Booker last October, the second in the past nine months.

“I am proud of the campaign we ran and the effort that my team put forth,” Lonegan said. “Unfortunately, we could not overcome the millions of dollars spent against us in negative attack ads.”

Currently, the state is represented by six Democrats and six Republicans. But Democrats are hoping to gain control of the 3rd District. MacArthur will now face Democrat Aimee Belgard, who prevailed in her party’s primary, in November’s general election.

In the other tight race, Watson Coleman defeated three other candidates vying for the Democratic nomination to replace retiring Democratic Rep. Rush Holt in the 12th District: state Sen. Linda Greenstein (D-Middlesex), Assemblyman Upendra Chivukula (D-Somerset) and Princeton University physics professor Andrew Zwicker.

New Jersey has not had a female member of Congress since Marge Roukema retired in 2003. But that will change in November. Watson Coleman will face Alieta Eck, a Somerset County doctor who ran unopposed for the Republican nomination. She will be considered the favorite because the district — which covers parts of Mercer, Middlesex, Somerset and Union counties — is heavily Democratic.

“I believe that Congress and our Legislature can always benefit from having someone that sees the issues and the needs and opportunities through the lens of both women and the minorities,” said Watson Coleman, who would also become the first African-American congresswoman in state history if elected.

Experts were expecting the battle between Watson Coleman and Greenstein to be close. But Watson Coleman drew about 42 percent of the vote, while Greenstein had 28, Chivikula 21, and Zwicker 7.

“I’ll figure out what I’m going to do and continue to be a senator,” Greenstein said. “I must enjoy my life with or without Congress, though I sure would have liked to go.”

Runyan and Holt aren’t the only New Jersey congressmen retiring. Democratic Rep. Rob Andrews of South Jersey’s 1st District stepped down earlier this year.

State Sen. Donald Norcross (D-Camden) beat two primary opponents last night for the Democratic nomination to run for Andrews’ seat. He’ll now face former Philadelphia Eagles linebacker Garry Cobb, who won a four-way race in the Republican primary.

Norcross, the brother of insurance executive George Norcross, arguably the top Democratic power broker in the state, will be favored to win in November because the district — which includes parts of Burlington, Camden, and Gloucester counties — leans Democratic.

In South Jersey’s 2nd District, Tuesday's primary sets up a general election match between veteran Republican Rep. Frank LoBiondo and Democrat Bill Hughes Jr. Hughes’ father held the seat from 1975 until his retirement in 1995. In 1992, Hughes Sr. fended off a challenge from LoBiondo, who went on to win the seat when Hughes did not seek re-election in 1994.

In Central Jersey’s 7th District, Clinton Mayor Janice Kovach won the Democratic nomination to try to unseat Republican Rep. Leonard Lance. Roy Cho, the son of Korean immigrants, won the Democratic primary in the 5th District to battle Republican Rep. Scott Garrett, New Jersey’s most conservative congressman.